1. Technical Field
The inventive concept relates generally to image sensors. More particularly, the inventive concept relates to unit pixels of image sensors, and to back-side illuminated image sensors including unit pixels.
2. Description of the Related Art
An image sensor is a device that transforms incident light to an electric signal. A charge coupled device (CCD) image sensor and a complementary metal oxide semiconductor (CMOS) image sensor are examples of different types of image sensors. To improve their sensing performance, either of these types of image sensor may be configured as a back-side illuminated image sensor (BIS). A BIS performs photoelectric transformation of incident light passing through a back surface of a semiconductor substrate.